好吧，我已经解决了这个问题。
所有你需要做的就是简单地抓取图像（info[UIImagePickerControllerOriginalImage] as UIImage）并保存到给定的目录。如果你只需要保存1张图片，它工作得很好。下面的代码ID。

func imagePickerController(picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [NSObject : AnyObject]) {
    let imageURL = info[UIImagePickerControllerReferenceURL] as NSURL
    let imageName = imageURL.path!.lastPathComponent
    let documentDirectory = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true).first as String
    let localPath = documentDirectory.stringByAppendingPathComponent(imageName)

    let image = info[UIImagePickerControllerOriginalImage] as UIImage
    let data = UIImagePNGRepresentation(image)
    data.writeToFile(localPath, atomically: true)

    let imageData = NSData(contentsOfFile: localPath)!
    let photoURL = NSURL(fileURLWithPath: localPath)
    let imageWithData = UIImage(data: imageData)!

    picker.dismissViewControllerAnimated(true, completion: nil)

}

在SWIFT 4中，您可以尝试以下操作：

func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : Any]) {
    
    
    if let imgUrl = info[UIImagePickerControllerImageURL] as? URL{
        let imgName = imgUrl.lastPathComponent
        let documentDirectory = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true).first
        let localPath = documentDirectory?.appending(imgName)
        
        let image = info[UIImagePickerControllerOriginalImage] as! UIImage
        let data = UIImagePNGRepresentation(image)! as NSData
        data.write(toFile: localPath!, atomically: true)
        //let imageData = NSData(contentsOfFile: localPath!)!
        let photoURL = URL.init(fileURLWithPath: localPath!)//NSURL(fileURLWithPath: localPath!)
        print(photoURL)
        
    }

    APPDEL.window?.rootViewController?.dismiss(animated: true, completion: nil)
}

对于Swift 5+ ;根据@Jaydip的回答

if let imgUrl = info[UIImagePickerController.InfoKey.imageURL] as? URL{
        let imgName = imgUrl.lastPathComponent
        let documentDirectory = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true).first
        let localPath = documentDirectory?.appending(imgName)

        let image = info[UIImagePickerController.InfoKey.originalImage] as! UIImage
        let data = image.pngData()! as NSData
        data.write(toFile: localPath!, atomically: true)
        //let imageData = NSData(contentsOfFile: localPath!)!
        let photoURL = URL.init(fileURLWithPath: localPath!)//NSURL(fileURLWithPath: localPath!)
        print(photoURL)

    }

func imagePickerController(picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [NSObject : AnyObject]) {
//this block of code grabs the path of the file   
let imageURL = info[UIImagePickerControllerReferenceURL] as NSURL
let imagePath =  imageURL.path!
let localPath = NSURL(fileURLWithPath: NSTemporaryDirectory()).URLByAppendingPathComponent(imagePath)

 //this block of code adds data to the above path
 let path = localPath.relativePath!
 let imageName = info[UIImagePickerControllerOriginalImage] as UIImage
 let data = UIImagePNGRepresentation(imageName)
 data?.writeToFile(imagePath, atomically: true)

//this block grabs the NSURL so you can use it in CKASSET
 let photoURL = NSURL(fileURLWithPath: path)
 }

检查这个解决方案。

import AssetsLibrary  

     func imagePickerController(picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : AnyObject]) {
          self.imagePicker = picker
          if let selectedImage = info[UIImagePickerControllerOriginalImage] as? UIImage {
            let controller = CropViewController(image: selectedImage )
            controller.delegate = self
            picker.presentViewController(controller, animated: true, completion: nil)
          }

       else if let imageUrl = info[UIImagePickerControllerReferenceURL] as? NSURL{
          let assetLibrary = ALAssetsLibrary()
          assetLibrary.assetForURL(imageUrl , resultBlock: { (asset: ALAsset!) -> Void in
            if let actualAsset = asset as ALAsset? {
              let assetRep: ALAssetRepresentation = actualAsset.defaultRepresentation()
              let iref = assetRep.fullResolutionImage().takeUnretainedValue()
              let image = UIImage(CGImage: iref)
              let controller = CropViewController(image: image)
              controller.delegate = self
              picker.presentViewController(controller, animated: true, completion: nil)
            }
            }, failureBlock: { (error) -> Void in
          })
        }
      }

在swift4中

func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : Any]) {        
    if let imgUrl = info[UIImagePickerControllerReferenceURL] as? URL{

        let imgName = imgUrl.lastPathComponent
        let documentDirectory = NSTemporaryDirectory()
        let localPath = documentDirectory.appending(imgName)

        let image = info[UIImagePickerControllerOriginalImage] as! UIImage
        let data = UIImageJPEGRepresentation(image, 0.3)! as NSData
        data.write(toFile: localPath, atomically: true)
        let photoURL = URL.init(fileURLWithPath: localPath)

    }

}

swift 4.2

func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey : Any]) {
    
    //obtaining saving path
    let fileManager = FileManager.default
    let documentsPath = fileManager.urls(for: .documentDirectory, in: .userDomainMask).first
    let imagePath = documentsPath?.appendingPathComponent("image.jpg")
    
    // extract image from the picker and save it
    if let pickedImage = info[UIImagePickerController.InfoKey.originalImage] as? UIImage {
        
        let imageData = pickedImage.jpegData(compressionQuality: 0.75)
        try! imageData?.write(to: imagePath!)
    }
}

谢谢

let imgUrl = info[UIImagePickerController.InfoKey.imageURL] as? URL